So, they started with his Ventana 29er hardtail mountain bike and added a Gates Belt Drive and Shimano Alfine Di2 11-speed. As the parts arrived, they realized that it would take some serious hacking to get the Gates cog to work with the Alfine hub. CP’s Michael Jellinek told us what had to be done:

“We had to custom machine down the motor unit, the belt cog, and custom space the internals of the hub and modify the bb/belt-ring spacing to make it work. It was a good two days of solid trial and error – but a fun winter project in rainy Portland! It turned out rock-solid.”

A bit scary considering the price point of the electronic internally geared hub, but always thrilled to see shops and riders make solutions for their customers and local conditions.

Click through for more pics…

They admit there’s a bit of cleaning up to do for the wiring, which they’re planning to do when the Di2 internal battery becomes readily available.

Related

Comments

Great project.
I’ve been thinking about a steel 29er, Alfine-11 (mechanical), Gates belt-drive bike for a while – seems to me like it would make for a pretty maintenance-free drive-train.
Would it be as difficult to set up mechanical Alfine for belt-drive as it was for this electronic version? Or were the complications specific to electronic?
Any advice very welcome. Or links to Alfine-11 / belt-drive bike projects.

Alfine-11 Gates belt-drive bikes are pretty standard, I have a city oriented one (BMC urbanchallenge) but the combination seem the most common Gates use if you need gears (and who doesn’t?). Budnitz bikes (that everyone here seem to love to hate) are using this combo too.

My main concern with current internal hubs is the concentration of weight over the rear wheel and how it affects handling and getting that wheel up and over and around trail obstacles. I love the concept and think more development should be focused on internal drivetrains. Weight will come down; reliability goes up.

Firstly the frame has to have a split in the stays for the belt to pass through. I’m not sure if the ventanna does have one, but I have seen mods.

Secondly making an Alfine work on a Mtb is a huge challenge! The issue being chain (belt) alignment and clearance of big tyres. Te belt has to have a certually straight, which is not an issue on city bikes as the tyres are not wide an do not rub on belt. On a wider tyre for Mtb, it forces te belt out further from the frame. This is typically not an issue on single speeds belt drives as you can change rear belt line on rear hub through use of spacers (or by using a specifically designed frame, single speed hub and crank with correct alignment). On the Alfine however, due to the shifting mech on the outside of hub, the cog is located a long way toward the centre of hub, meanin if you go for correct belt line, the belt fouls on the wide Mtb tyre.

I would be interested in seeing the mods they have done to the rear cog to make this work. I know one of the custom frame builders was making an offset gates rear cog to make this work.

the only reason for this is to give the appearance of a singlespeed, while having gears. I take a chain tool and a few extra links with me. How many of us can honestly say that they pack an extra gates carbon belt when they ride in the mountains?

For an update on the status of the belted DI29er, check out http://www.cyclepathnw.com. Nelson’s been beating this bike down and it’s holding up like a champ! We should note, this build utilizes the centerline belt and cog system from Gates, not the original belt/cog design that slipped like mad.

@Kevin – The only problem I’ve had with my Alfine 11, is road crap getting stuck in the groove where the shifter cable wraps and causes mis-shifting in higher gears. Therefore the electronic shifter is appealing because it may be _more_ dependable, than the cable.
I’ve been using an Alfine 11, for almost 2 years (16,000km), on my all weather commuter.

MissedThePoint – as for the Alfine in the cold, it’s no worse than any other hub. The 11 spd runs in an oil bath. I start to notice increased resistance when temps drop below 10 degrees. But in temps below that every rotating part in the bike slows you down 🙂

OneGearGuy – The weight difference over an externally geared wheel is negligible. The primary difference is it’s all rotating weight, so there is some additional inertia to over come when accelerating. That and the IGH/belt combination is a little less efficient. That said, I love beltdrive and do not want to go back to greasy drivetrains 🙂

We have had many people email us asking for step-by-step directions on how to do this conversion. Many of them have been unhappy when we opt to not share the knowledge. I figured we’d give some insight as to our decision:

we spent more than three days working out this special build. I paid over three days of wages for several people not to mention the expense of all our shop resources. It was an awesome feat that we wanted to give up on several times because of all the intricacies and dead-ends we hit. Both Shimano and Gates said it couldnt be done. This was to be a showpiece for our shop. Shimano emailed us right after this article hit asking for photos and step by step tips. Much as they dont share their trademark secrets when they develop a product, we werent going to give our hard work and expenses away for free. What we did was very technical and would require the use of a machinist to do it right. So, its not something we’d want to put out for the general public to try. It’d be a recipe for disaster, especially considering the lengths we went to voided any and all warranties to the products we altered. We are happy to make this conversion a reality for others at this point, but it will come at a cost equal to the effort put into it. This next time around it wont take anywhere close to the same amount of time, but there are things out of our hands that can make or break the success of the project outside of the conversion itself (ie: chainline of a given frame. crank vs frame compatibility. etc). These are further reasons this task is best left to your professional bike shop.

So I have an alfine 8 with the original belt drive and I had a lot of slipping issues. I finally got it under a lot more tension then I am comfortable with but it doesn’t slip. It does however cause a lot more drag under all that tension. The bike really doesn’t like to free spin the rear with without the cranks rotating on the stand. If you hold the pedal and spin the rear wheel it is as if the brakes are being very slightly applied.

Maintenance is great of course. But I think if I went IGH on a mountain bike I would run a chain. The above machine is a get around town cruiser and for that it is fine.

Really want a IGH 29ner but worried the hubs all want more gear inches in the system then I would want.

About Us

Bikerumor.com is the world’s largest cycling tech blog. Our passion is the products, technology and people that make them. We cover the shiny new things, with in-depth interviews and detailed stories about how the bicycles and components work, plus reviews to see if they live up to the hype. We love learning the technology and celebrating innovation at every level -from crowdfunded start ups to major global brands- and sharing it all here with you!

Want to Contribute?We’re always looking for enthusiastic, positive and talented writers that know their way around both a bicycle and sentence structure. We're also looking for a good Sales person to help grow our business